India, Dec. 9 -- More than two decades after allegations of large-scale manipulation in examinations conducted by the Maharashtra Public Service Commission (MPSC) surfaced in 2001, the prosecution's case in a clutch of linked trials before a special court is showing visible strain - key witnesses are disowning statements, disputing signatures and citing fading memory.

Over the last week, the court has recorded the depositions of several retired government officials who served as invigilators during the 1999-2001 examinations, as well as candidates whose results were allegedly tainted by malpractice.

A recurring pattern has emerged, with witnesses denying that signatures on answer sheets are theirs, saying they cannot recall events after...